A steel structure may contain main structural members, such as columns, main beams, secondary beams and bracings, connected as an integrated structure via connecting joints.
At present, the most commonly used method for connecting joints include the use of a high strength bolt connection and welding. Generally, in a steel fabrication factory, steel members (such as, beams and columns) and connecting plates are prefabricated, the connecting plates and stiffener plates are welded, and bolt holes are drilled in advance at locations where a bolt connection is needed. Then, the prefabricated members are transported to the construction site, hoisted to proper position and subsequently connected by using high strength bolts or welding.
The above-described methods for connecting joints may suffer the following deficiencies:
1) When using the high strength bolt connection method, each joint may need dozens or even hundreds of bolt holes on the members and connecting plates, causing significant increase in the time and cost of processing.
2) Errors usually occur since components are not mass-produced in the fabrication factory. As a result, it can be difficult to connect components due to a composition of prefabrication errors caused by different components and production processes.
3) After the steel members are transported to the construction site and hoisted in place when connected by bolts, manual fixing for the bolts are required. For fixing each bolt, three working procedures may be needed: that is, temporary fixing of the bolt, an initial screwing and final screwing of the bolt, which greatly increases on-site workload and cost.
4) When connected by onsite welding, generally a pre-heating process needs to be performed prior to welding, which not only increases the on-site workload and cost but also easily affected by welder's experience and proficiency, the welding procedure and welding environment such as weather condition and welding position. Thus, this makes it difficult to ensure a good quality for on-site welding.